make-bootstrap-tools: fix with latest coreutils

Since gcc.lib/lib64 is a symlink to 'lib', the use of
"lib*/libgcc_s.so*" triggered a warning (error) with
the latest coreutils.  Essentially we were doing:

$ cp a/x b/x y/

And latest coreutils rejects such invocations.

Just copy from 'lib', lib64 is a link to it anyway.

* Nothing else in this file bothers looking at lib*
* AFAICT lib* only ever possibly matched lib64 anyway